Apparatus for optically mixing colors



Jan. 13, 1959 s. H. BIRDSEYE APPARATUS FOR OPTICALLY MIXING COLORS 2Sheets-Sheet 1 Filed Oct. 19, 1954 Sidney H. Birdseye IN VEN TOR.

, 9 BY weed.

Jan. 13, 1959 s. H. BIRDSEYE APPARATUS FOR OPTICALLY MIXING COLORS FiledOct. 19, 1954 2 Sheets-Sheet 2 N% wk h t wk on mm mm .m\ C y R mm mm anSidney hf Birdseye INVENTOR.

s BY wan/6' 3/0...

Auorn United States Patent 2,8618% Patented Jan. 13, 1959 2,867,916APPARATUS FOR OPTICALLY MIXING COLORS Sidney H. Birdseye, Arlington,Va., assignor of fifty percent to Bertram Michael Landemann,

. Application October 19, 1954, Serial No. 463,155

4 Claims. (Cl. 35-19) thereby adjusting the intensity of the variouscolored lights which permits the mixing of these lights into a resultantcolor tint of spectral quality.

Another object of the present invention isto provide an apparatus foroptically mixing colors which will provide various shades of tintedcolors on a viewing screen or ground lens, thereby permitting theformation of colors with a desired, spectral tint.

A still further object of the present invention is to provide anapparatus for optically mixing colors conformable to the precedingobjects wherein the variable density scale is calibrated so that therelative intensity of the various colors may be determined for referencepurposes. 7

Still another important object of the present invention is to provide anapparatus for optically combining colors which is simple inconstruction, easy to use, adaptable for various uses and purposes andrelatively inexpensive to manufacture.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation, as more fully hereinafter described and claimed, reference,being had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

Figure 1 is a side elevational view of the apparatus utilized inoptically mixing colors with portions thereof broken away showingvarious details of construction;

Figure 2 is a top plan view of the construction of Figure 1 showing therelationship of various elements of the invention;

Figure 3 is a transverse, vertical sectional view taken substantiallyupon the plane, passing along section line 33 of Figure 1 showing thedetails of construction of the density scale reels;

Figure 4 is a detailed sectional view taken substantially upon a planepassing along section line 44 of Figure 2 showing the details ofconstruction of the color filter holder and the guide for the variabledensity scale;

Figure 5 is a perspective view showing the construction of one of thecolor filters; and

Figure 6 is a fragmentary perspective view showing the construction ofthe density scale having blocks thereon of varying degrees ofopaqueness.

Referring now specifically to the drawings, it will be seen that thenumeral 10 generally designates the apparatus for optically combiningand mixing colors of the present invention. The apparatus 10 generallyincludes a; supporting base 12 of any desirable rectangular configuration which is provided at one end thereof with an upstanding andinverted U-shaped supporting bracket 1.4 havinga socket 16 receiving aprojector-type light bulb 18 therein. A suitable electrical conductor 20is at- Washington,

tached to the socket 16 and an on-and-ofi switch 22 is provided forcontrolling the electrical current to the light source 18. A casing 24is provided forwardly of the light source 18 and may be of any desirableopaque construction' and positioned behind the light source 18 is aparabolic reflector 26 having a suitable reflective surface on the innersurface thereof.

Positioned in a horizontal plane and extending through the casing 24 ina radial position are three rods 28, 30 and 32 which are constructed of.plastic material, such as Lucite, which transmits light from the sourceof light 18 along the longitudinal length of the rods 28, 30 and 32,wherein the rods 28, 30 and 32 extend in a horizontal plane with theouter rods 28 and 32 diverging and then extending in parallel spacedrelation to the center rod 30. The other ends of the rods 28, 30 and 32converge with the outer rods 28 and 32 converging towards the center rod30, wherein they terminate in a Lucite collecting rod 34 which is largerthan the rods 28, 30 and 32. Positioned at the forward end of the Luciterod 34 is a projecting lens 36 which is removably positioned thereon bya screw threaded cap 38 which permits removal or replacement of theprojecting lens 36.

The Lucite collecting rod 34 used to mix colors is supported on anupstanding bracket 40 which terminates in a U-shaped portion 42 whichengages and supports the Lucite rod 34. The inner end of the Lucite rod34 is positioned in a split cap 44 having clamp screws 46 detachablyclamping the Lucite rod 34 in the split cap 44. With this particularconstruction, it will be noted that both the lens 36 and the Lucitemember 34 may be removed and changed as desired.

Positioned centrally in each of the rods 28, 30 and 32 is a color filterholder and a density scale holder generally designated by the numeral48, the details of which are illustrated in Figure 4.

Referring specifically to the holder 48, it will be see that this deviceis generally formed in a tubular polygonal sleeve 50 having an entranceslot 52 for slidably and removably positioning a primary optical colorfilter 54 which may be straight or provided with an offset handle. Therod 30 as Well as the other rods are sectional and terminate in anenlarged polygonal collar 56 and the filter 54 is positioned betweenthe. enlarged collarv 56 on one portion of the rod 30, and the enlargedcollar 58 on the other portion of the rod 30 wherein light will passthrough the filter 54 along the rod 38. Extending integrally from theupper and lower surface of the sleeve 50 is a tubular guide 60 forreceiving a movable density scale 62 which is positioned forwardly ofthe color filter 54. The density scale ,62 is'provided with a series ofblocks 64 of varying degrees of opaqueness or transparency wherein theintensity of the light passing through the color filter 54 may bevaried. The tubular member 60 extending upwardly and downwardly from thesleeve 50 terminates in cylindrical housings 66 and 68, with one of thecylindrical housings 66 being positioned above the rod and one of thehousings 68 being positioned below the cylindrical rod 30.

The upper cylindrical housing 66 is provided with a re movable cap 78and a central handle and shaft 72 on which a reel 74 is positioned forreceiving the density scale 62. The lower cylindrical housing 68 isprovided with a removable cap 76 having a cylindrical reel 78 mountedtherein for receiving the density scale 62. The reel 78 is secured to arotatable shaft 80 which projects outwardly of the cap 76 and isprovided with a pointer 82 thereon for registry with indicia 84 on theouter surface of the lower cap 76, thereby calibrating the density scale62 on the calibrated indicia 84 for determining the position of thedensity scale so that the relative intensity of the light passingthrough each of the rods 28, 30, and

32 may be determined. It is noted that each of the rods 28, 30 and 32 isprovided with an identical structure for a supporting a color filter andsupporting the movable density scale 62. It is'noted that the colorfilter 62 ,on

the rods 28 and 32 is removable from the side while the color filter 62on the central rod 30 is removable from the top.

.The upper and lower reel housing 66 and 68 are supported from rearbrackets 86 and a forward bracket 88 is provided for supporting thehousing 66and .68 in proper relation to the central rod 30. The bracket38 is positioned forwardly of the brackets 86.

In operation, the light from the light source 18 passes along thetransmission rods 28, 30 and 32 through the color filters 54 which maybe of any of the primary colors and then through the density scale 62which varies the intensity of the light passing along-the rods 28, 30and 32. This varies the intensity of the prime colors and the light thenpasses into the collecting rod 34 and is projected by the lens 36 onto asuitable viewing area, or the device may be utilized with a glass screenfor forming a viewing area substantially in the plate of the projectinglens 36.

If desired, the entire device may be covered with a removable cover 90,and the source of light may be ventilated, and the particular structuraldetails for mixing colors has been previously described.

The white light maybe transmitted from the source through the primarycolor filters and the density gray scales by use of tubes employing aseries of mirrors therein or any suitable system of lenses, prisms orcombination thereof, and then, projecting the tints from the hollowtubes. It will be understood that a minimum of three primary colors areto be used and it may be advisable to add one or more secondary colorswith accompanying transmission means such as rods or tubes plus colorfilters and density scales.

It will be understood that the device may be utilized in any particularorientation in which it is desirable to mix colors for various purposeswhere resultant tints of true spectral quality are essential, such ascomparative analysis, interior decoration, testing purposes,metallurgical heat testing and control, and paint manufacture. The scalemay be calibrated to set up various standards and by computing variousproblems with these standards, it will be possible to establish a testand analysis procedure.

From the foregoing, the construction and operation of thejdevice will bereadily understood and further explanation is believed to beunnecessary. However, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction shown and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the appended claims.

What is claimed as new is as follows:

1. A color mixing device comprising a source of light, means fortransmitting the light along a plurality of paths, means for coloringthe light in each path, means for varying the intensity of the coloredlight in each path, and means for converging and projecting the coloredlight thereby forming a variable resultant color, said means forconverging and projecting the colored lights including a solidcollecting and mixing rod for projecting the mixed colors onto a viewingarea in true spectral quality.

2. A color mixing device comprising a source of light, means fortransmitting the light along a plurality of paths, means for coloringthe light in eachpath, means for varying the intensity of the coloredlight in each path, and means for converging and projecting the coloredlight thereby forming a variable resultant color of true spectralquality, said light transmitting means including a plurality of lighttransmitting rods, said rods extending radially from said light sourcein a plurality of parallel paths, said rods converging radially inwardlyremote from said light source for directing the light toward a commonprojection point, said means for coloring the light including aremovable color filter positioned in each path of light, said filtersimparting prime color to the light, said filters being insertable forchanging the color of each light path, said means for varying theintensity of the light in each path including a movable density scalepositioned adjacent the coloring means for varying the intensity of thelight after it has been colored, said scale being wound on reels onopposite sides of said path of light for positioning selective areas ofthe density scale in the path of light, and a calibrated scale on one ofsaid reels for indicating the portion of the scale in the path of lightthereby determining the intensity of the light.

3. A color mixing device comprising a source of light, means fortransmitting the light' along a plurality of paths, means for coloringthe light in each path, means for varying the intensity of the colored.light in each path, and means for converging and projecting the coloredlight thereby forming a variable resultant color,

said light transmitting means including a plurality. of lighttransmitting rods, said rods extending radially from said lightsource'and bending the light to travel in a plurality of parallel paths,said rods converging v radially inwardly remote from said light sourcefor directing the light toward a common projection point, said means forcoloring the light including a removable color filter positioned in eachpath of light, said filters imparting prime color to the light, saidfilters being insertable for changing the color-of each light path, saidmeans for varying the intensity of the lightin each path including amovable density scale positioned adjacent the coloring means for varyingthe intensity of the light after it has been colored, said scalebeing'wound on reels on opposite sides of said path-of light forpositioning selective areas of the density scale in the path'of light,and a calibrated scale on one of said reels for indicating the portionof the scale in the path of light thereby determining the intensity ofthe light, said means for converging and projecting the colored lightsincluding a solid collecting and mixing rod for projecting the mixedcolors onto a viewing area in true spectral quality.

4. A device for optically mixing primary colors and producing colortints of true spectral quality comprising a source of white light ofsubstantially constant intensity, a plurality of light transmitting rodsreceiving light from said source, a removable prime color filterReferences Cited in the file of this patent I UNITED STATES PATENTS ,091Parsons -L. June 21, 1932 1,981,999 French Aug. 20, 1932 72.646 SchmidtFeb. 10, 1942 67 Ford .a July 25, 1944 2,431,091 Thomas NOV. 18, 1947 91Morrison a, Jan; 10, 1950 2,589,569 ,Peter Mar. 18, 1952 :OTHERREFERENCES p g Light With Acrylic Materials by Henry Pear- O rMQdern.stics, August 1946, pp. 123-127..

and bending the light to travel

